Here we will make an attempt at describing the non-Standard extensions to
the library. Some of these are from SGI's STL, some of these are GNU's,
and some just seemed to appear on the doorstep.

Before you leap in and use any of these
extensions, be aware of two things:

Non-Standard means exactly that.

The behavior, and the very
existence, of these extensions may change with little or no
warning. (Ideally, the really good ones will appear in the next
revision of C++.) Also, other platforms, other compilers, other
versions of g++ or libstdc++ may not recognize these names, or
treat them differently, or...